This disclosure relates generally to stabilizers for vehicle suspension systems, and more particularly to a method and system for controlling roll control actuators.
Hydraulically actuated roll control systems for selectively controlling roll characteristics of vehicle suspension systems are known. One such system was disclosed in U.S. Pat. No. 3,197,233. That system utilized a roll control actuator hydro-mechanically coupling first and second (e.g., left and right) torsion bars. The roll control actuator comprised a rotary hydraulic cylinder including a cylindrical housing having two radially oriented ribs projecting into a cylindrical space of a housing. A vane-type swinging piston has two vanes, and the ribs and vanes separate the cylindrical space into four chambers.
A different type of roll control actuator was disclosed in U.S. Pat. No. 6,361,033. As opposed to a rotary hydraulic cylinder, the roll control actuator comprised an axially moving piston driving an internally disposed annular member having an internal ball spline. The ball spline couples to a first torsion bar and an external large helix angle ball screw, which couples to a second torsion bar. Axial thrust imposed upon the annular member results in torque being imposed between the first and second torsion bars.
Simplified controls of prior art roll control actuators are not well developed. For example, one type of roll control device is unnecessarily complex in that it utilizes two proportional solenoid controlled valves for controlling differential pressure values in front and rear stabilizer roll control actuators. Two solenoid controlled valves are also used with one of them having seven ports. Furthermore, a roll control device using proportional solenoid controlled valves that are open center valves, relies upon continuous fluid flow derived from a compound engine driven power steering pump, which is not desired.
What is needed is a simplified roll control device having improved performance characteristics. A more direct electronic control is also desired.